Bone Sharon E, Gonneea Meagan Eagle, Charette Matthew A
Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, USA.
Environ Sci Technol. 2006 May 15;40(10):3273-8. doi: 10.1021/es052352h.
Biogeochemically modified pore waters from subterranean estuaries, defined as the mixing zone between freshwater and saltwater in a coastal aquifer, are transported to coastal waters through submarine groundwater discharge (SGD). SGD has been shown to impact coastal and perhaps global trace metal budgets. The focus of this study was to investigate the biogeochemical processes that control arsenic cycling in subterranean estuaries. Total dissolved As, as well as a suite of other trace metals and nutrients, were measured in a series of wells and sediment cores at the head of Waquoit Bay, MA. Dissolved As ranged from below detection to 9.5 microg/kg, and was associated with plumes of dissolved Fe, Mn, and P in the groundwater. Sedimentary As, ranging from 360 to 7500 microg/kg, was highly correlated with sedimentary Fe, Mn, and P. In addition, amorphous Fe (hydr)oxides were more efficient scavengers of dissolved As than the more crystalline forms of solid-phase Fe. Given that dissolved As in the surface bay water was lower than within the subterranean estuary, our results indicate that the distribution and type of Fe and Mn (hydr)oxides in coastal aquifers exert a major influence on the biogeochemical cycling of As in subterranean estuaries and, ultimately, the fate of groundwater-derived As in marine systems influenced by SGD.
来自地下河口的生物地球化学改性孔隙水，被定义为沿海含水层中淡水和盐水的混合区，通过海底地下水排放（SGD）输送到沿海水域。研究表明，海底地下水排放会影响沿海乃至全球的痕量金属收支。本研究的重点是调查控制地下河口砷循环的生物地球化学过程。在马萨诸塞州瓦夸特湾源头的一系列水井和沉积物岩心中，测量了总溶解砷以及其他一系列痕量金属和营养物质。溶解砷的含量范围从低于检测限到9.5微克/千克，并且与地下水中溶解的铁、锰和磷的羽状物有关。沉积砷的含量范围从360到7500微克/千克，与沉积铁、锰和磷高度相关。此外，非晶态铁（氢）氧化物比结晶度更高的固相铁形式更有效地清除溶解的砷。鉴于表层海湾水中的溶解砷低于地下河口内的溶解砷，我们的结果表明，沿海含水层中铁和锰（氢）氧化物的分布和类型对地下河口砷的生物地球化学循环以及最终受海底地下水排放影响的海洋系统中源自地下水的砷的归宿具有重大影响。
